Playpen is usually used to confine a small child within a safety area without exposing to risks before he/she can walk when adults are not able to take care of the child constantly. The adults generally will provide toys in the playpen or hang toys on a toy bracket to amuse the child. For instance, U.S. Pat. No. 4,750,509 discloses a folding device of a tent-frame work that includes a central hub member and a plurality of ribs. The ribs are connected radial to the central hub member when in use. It takes a lot of time to set up.